Our old SharePoint 2010 had a special document type "release note", which created a new word document using a specific .dot or .dotx word template:

Now we moved to SharePoint online (office 365) and a lot of documents were copied. Now when I duplicate an existing release note document or open one, I see that it still loads the template from our old SharePoint 2010 server:

During splash screen of word you suddenly see it pointing to our old SharePoint server to load the template:

Hope the question was clear, as I don't know how this was configured in SharePoint 2010, nor how to modify this in SharePoint Office 365..